A large static magnetic field is used by Magnetic Resonance Imaging (MRI) scanners to align the nuclear spins of atoms as part of the procedure for producing images within the body of a patient. This large static magnetic field is referred to as the B0 field.
During an MRI scan, Radio Frequency (RF) pulses generated by a transmitter coil cause perturbations to the local magnetic field, and RF signals emitted by the nuclear spins are detected by a receiver coil. These RF signals are used to construct the MRI images. These coils can also be referred to as antennas. Further, the transmitter and receiver coils can also be integrated into a single transceiver coil that performs both functions. It is understood that the use of the term transceiver coil also refers to systems where separate transmitter and receiver coils are used. The transmitted RF field is referred to as the B1 field.
MRI scanners are able to construct images of either slices or volumes. A slice is a thin volume that is only one voxel thick. A voxel is a small volume over which the MRI signal is averaged, and represents the resolution of the MRI image. A voxel may also be referred to as a pixel herein.
International patent application publication WO 2008/132659 A2 discloses a magnetic resonance device in which the device acquires a plurality of k-space blades according to the PROPELLER scheme. The device is arranged to weight the acquired MR data, wherein weighting factors are computed on the basis of acquisition times for contrast manipulation, correlation measure for motion compensation, and on the basis of the geometry of the overlapping areas of the k-space blades. The paper ‘Free-breathing myocardial perfusion MRI using SW-CG-HYPR and motion correction’ by L. Ge et al in MRM64(2010)1148-1154 discloses an ECG triggered multi-slice gradient echo sequence with radial k-space sampling. From six slices following three saturation recovery preparations in each cardiac cycle a composite image is reconstructed. Low-resolution images reconstructed from the center of k-space from each cardiac cycle are compared to the composite image. From this comparison translation and rotation of the heart are detected in the image domain.